Tail-to-tail Research Articles

Magnetoelectric Phase Control at Domain‐Wall‐Like Epitaxial Oxide Multilayers

AbstractFerroelectric domain walls are nanoscale objects that can be created, positioned, and erased on demand. They often embody functional properties that are distinct from the surrounding bulk material. Enhanced conductivity, for instance, is observed at charged ferroelectric domain walls. Regrettably, domain walls of this type are scarce because of the energetically unfavorable electrostatics. This hinders the current technological development of domain‐wall nanoelectronics. Here this constraint is overcome by creating robust domain‐wall‐like objects in epitaxial oxide heterostructures. Charged head‐to‐head (HH) and tail‐to‐tail (TT) junctions are designed with two ferroelectric layers (BaTiO3 and BiFeO3) that have opposing out‐of‐plane polarization. To test domain‐wall‐like functionalities, an ultrathin ferromagnetic La0.7Sr0.3MnO3 layer is inserted into the junctions. The interfacial electron or hole accumulation at the interfaces, set by the HH and TT polarization configurations, respectively, controls the LSMO conductivity and magnetization. Thus it is proposed that trilayers reminiscent of artificial domain walls provide magnetoelectric functionality and may constitute an important building block in the design of oxide‐based electronic devices.

3D Domain Arrangement in van der Waals Ferroelectric α‐In2Se3

AbstractOne of the exceptional features of the van der Waals (vdW) ferroelectrics is the existence of stable polarization at a level of atomically thin monolayers. This ability to withstand a detrimental effect of the depolarization fields gives rise to complex domain configurations characterized, among others, by the presence of layered “antipolar” head‐to‐head (H‐H) or tail‐to‐tail (T‐T) dipole arrangements. In this study, tomographic piezoresponse force microscopy (TPFM) is employed to study the 3D polarization arrangement in vdW ferroelectric α‐In2Se3. Sequential removal of thin layers from the polar surface using the PFM tip reveals a complex 3D profile of the domain walls in the α‐In2Se3 crystals. Antiparallel domain layers stacked along the polar direction are also observed by PFM imaging of the non‐polar surfaces showing that H‐H and T‐T domain boundaries are commonly present in α‐In2Se3. Application of TPFM to the electrically written domains allows evaluation of their geometrical lateral‐to‐vertical size aspect ratio, which shows a strong prevalence for the sidewise expansion in comparison to the forward growth. Local I–V measurements reveal a strong polarization direction dependence of conductivity due to the modulation of the energy barrier height as corroborated by theoretical modeling.

Oxygen vacancies stabilized 180° charged domain walls in ferroelectric hafnium oxide

Ferroelectric domain walls (DWs) are spatial interfaces separating domains with distinct polarization orientations. Among these DWs, some can carry bound charges and display metallic-like conductivity. The feature is highly of interest for future nanoelectronics. However, the inherent instability of charged domain walls (CDWs) has posed a critical challenge for their experimental exploration. This Letter reports the head-to-head (HH) and tail-to-tail (TT) 180° CDWs within the context of ferroelectric hafnium oxide. We proposed that oxygen vacancy is a crucial factor stabilizing the periodic CDWs. Through meticulous first-principles calculations, we elaborated on the intricate properties of these CDWs, including their polarization profiles, and potential and charge distributions. Furthermore, we calculated the energy barrier for layer-by-layer propagation of a HH wall and carefully discussed the migration of a TT wall with oxygen vacancy. Our study can shed more light onto the characteristics of CDWs and their implications to hafnia-based ferroelectric devices.

Electromechanics of Domain Walls in Uniaxial Ferroelectrics

AbstractPiezoresponse force microscopy (PFM) is used for investigation of the electromechanical behavior of the head‐to‐head (H‐H) and tail‐to‐tail (T‐T) domain walls on the non‐polar surfaces of three uniaxial ferroelectric materials with different crystal structures: LiNbO3, Pb5Ge3O11, and ErMnO3. It is shown that, contrary to the common expectation that the domain walls should not exhibit any PFM response on the non‐polar surface, an out‐of‐plane deformation of the crystal at the H‐H and T‐T domain walls occurs even in the absence of the out‐of‐plane polarization component due to a specific form of the piezoelectric tensor. In spite of their different symmetry, in all studied materials, the dominant contribution comes from the counteracting shear strains on both sides of the H‐H and T‐T domain walls. The finite element analysis approach that takes into account a contribution of all elements in the piezoelectric tensor, is applicable to any ferroelectric material and can be instrumental for getting a new insight into the coupling between the electromechanical and electronic properties of the charged ferroelectric domain walls.

Dimerization of cholesterol permits its binding to lipid-free apoA-I

Background and Aims : To model the interaction of lipid-free apoA-I with cholesterol molecules that exist in various self-associated forms in extracellular space. Cholesterol dimerization is exploited to reconcile the existing experimental data on cholesterol binding to apoA-I with extremely low critical micelle concentration of cholesterol.Methods: The interaction of differently self-associated lipid-free apoA-I with cholesterol monomer and tail-to-tail (TT) or face-to-face (FF) cholesterol dimer was modelled with Schrödinger package. Two crystal structures of 1-43 N-truncated apolipoprotein Δ(1-43)A-I tetramer (PDB ID: 1AV1, structure B), 185-243 C-truncated apolipoprotein Δ(185-243)A-I dimer (PDB ID: 3R2P, structure M) were exploited.Results: Cholesterol monomers bind to multiple binding sites in apoA-I monomer, dimer and tetramer with low, moderate and high energy, still insufficient to overcome the thermodynamic restriction by cholesterol micellization (-52.8 kJ/mol). However, apoA-I monomer and dimer existing in structure B, that contain nonoverlapping and non-interacting pairs of binding sites with high affinity for TT and FF cholesterol dimers, can bind in common 14 cholesterol molecules that correspond to existing values. ApoA-I monomer and dimer in structure M can bind in common 6 cholesterol molecules. The values of respective total energy of cholesterol binding for both B and M structures exceed the free energy of cholesterol micellization.Conclusions: Cholesterol dimers may simultaneously interact with extracellular monomer and dimer of lipid-free apoA-I, that accumulate at acid pH in atheroma. The thermodynamically allowed apolipoprotein-cholesterol interaction outside the macrophage may represent a new mechanism of cholesterol transport by apoA-I from atheroma, in addition to ABCA1-mediated cholesterol efflux. Background and Aims : To model the interaction of lipid-free apoA-I with cholesterol molecules that exist in various self-associated forms in extracellular space. Cholesterol dimerization is exploited to reconcile the existing experimental data on cholesterol binding to apoA-I with extremely low critical micelle concentration of cholesterol. Methods: The interaction of differently self-associated lipid-free apoA-I with cholesterol monomer and tail-to-tail (TT) or face-to-face (FF) cholesterol dimer was modelled with Schrödinger package. Two crystal structures of 1-43 N-truncated apolipoprotein Δ(1-43)A-I tetramer (PDB ID: 1AV1, structure B), 185-243 C-truncated apolipoprotein Δ(185-243)A-I dimer (PDB ID: 3R2P, structure M) were exploited. Results: Cholesterol monomers bind to multiple binding sites in apoA-I monomer, dimer and tetramer with low, moderate and high energy, still insufficient to overcome the thermodynamic restriction by cholesterol micellization (-52.8 kJ/mol). However, apoA-I monomer and dimer existing in structure B, that contain nonoverlapping and non-interacting pairs of binding sites with high affinity for TT and FF cholesterol dimers, can bind in common 14 cholesterol molecules that correspond to existing values. ApoA-I monomer and dimer in structure M can bind in common 6 cholesterol molecules. The values of respective total energy of cholesterol binding for both B and M structures exceed the free energy of cholesterol micellization. Conclusions: Cholesterol dimers may simultaneously interact with extracellular monomer and dimer of lipid-free apoA-I, that accumulate at acid pH in atheroma. The thermodynamically allowed apolipoprotein-cholesterol interaction outside the macrophage may represent a new mechanism of cholesterol transport by apoA-I from atheroma, in addition to ABCA1-mediated cholesterol efflux.

Conductions through head-to-head and tail-to-tail domain walls in LiNbO3 nanodevices

Conducting domain walls in an insulating ferroelectric matrix are interesting for the development of next generation multifunctional nanodevices with large output powers. However, electrical conductions are diversified among head-to-head (H-H), neutral (N), and tail-to-tail (T-T) domain walls (DWs) with disputable conduction mechanisms. It is generally accepted that the charged DWs are more electrically conductive than the neutral DWs. However, the charged walls are unstable due to high depolarization energies. Here, we stabilized the H-H DWs, NDWs and T-T DWs within a LiNbO3 transistor by controlling charge injection in compensation of the domain boundary charge under applied drain–gate, drain–source and gate–source voltages. The walls were created through the local 180° domain reversals in different inclined angles, and the transistors in different sizes were fabricated at the surfaces of 5 mol.% MgO-doped LiNbO3 single crystals in monodomain patterns. The NDWs are positively charged due to small inclination angles (~1°) and local sideways meandering behavior of the charged dipoles with electrical conduction that is three orders of magnitude higher than that across the T-T DWs but is one order of magnitude lower than that across the H-H DWs. Voltage dependences of wall currents can be fitted according to the space-charge-limited current equation with an exponential coefficient varying between 2.1 and 3.7 in some specific voltage ranges, implying discontinuous domain retraction in different inclined wall angles against the reduced applied voltage to affect the wall current. This finding provides the fundamental physics to improve domain wall conduction via domain reconstruction and broadens the domain wall application in future nano-devices.

Interaction of lipid-free apolipoprotein A-I with cholesterol revealed by molecular modeling

We report the modeling of the interaction of differently self-associated lipid-free apoA-I with cholesterol monomer and tail-to-tail (TT) or face-to-face (FF) cholesterol dimer. Cholesterol dimerization is exploited to reconcile the existing experimental data on cholesterol binding to apoA-I with extremely low critical micelle concentration of cholesterol. Two crystal structures of 1–43 N-truncated apolipoprotein Δ(1-43)A-I tetramer (PDB ID: 1AV1, structure B), 185–243 C-truncated apolipoprotein Δ(185-243)A-I dimer (PDB ID: 3R2P, structure M) were analyzed. Cholesterol monomers bind to multiple binding sites in apoA-I monomer, dimer and tetramer with low, moderate and high energy (−10 to −28 kJ/mol with Schrödinger package), still insufficient to overcome the thermodynamic restriction by cholesterol micellization (−52.8 kJ/mol). The binding sites partially coincide with the putative cholesterol-binding motifs. However, apoA-I monomer and dimer existing in structure B, that contain nonoverlapping and non-interacting pairs of binding sites with high affinity for TT and FF cholesterol dimers, can bind in common 14 cholesterol molecules that correspond to existing values. ApoA-I monomer and dimer in structure M can bind in common 6 cholesterol molecules. The values of respective total energy of cholesterol binding up to 64.5 and 67.0 kJ/mol for both B and M structures exceed the free energy of cholesterol micellization. We hypothesize that cholesterol dimers may simultaneously interact with extracellular monomer and dimer of lipid-free apoA-I, that accumulate at acid pH in atheroma. The thermodynamically allowed apolipoprotein-cholesterol interaction outside the macrophage may represent a new mechanism of cholesterol transport by apoA-I from atheroma, in addition to ABCA1-mediated cholesterol efflux.

First-principles study of two-dimensional electron and hole gases at the head-to-head and tail-to-tail 180∘ domain walls in PbTiO3 ferroelectric thin films

We study from first-principles the structural and electronic properties of head-to-head (HH) and tail-to-tail (TT) 180$^\circ$ domain walls in isolated free-standing PbTiO$_{3}$ slabs. For sufficiently thick domains ($n$ = 16 unit cells of PbTiO$_{3}$), a transfer of charge from the free surfaces to the domain walls to form localized electron (in the HH) and hole (in the TT) gases in order to screen the bound polarization charges is observed. The electrostatic driving force behind this electronic reconstruction is clearly visible from the perfect match between the smoothed free charge densities and the bound charge distribution, computed from a finite difference of the polarization profile obtained after the relaxation of the lattice degrees of freedom. The domain wall widths, of around six unit cells, are larger than in the conventional 180$^\circ$ neutral configurations. Since no oxygen vacancies, defects or dopant atoms are introduced in our simulations, all the previous physical quantities are the intrinsic limits of the system. Our results support the existence of an extra source of charge at the domains walls to explain the enhancement of the conductivity observed in some domains walls of prototypical, insulating in bulk, perovskite oxides.

Effect of the Nature and the Position of Defects on the Chiral Expression in Poly(3-alkylthiophene)s

Polymers produced with the most used controlled polymerization method with the simplest initiators, namely the Kumada catalyst transfer condensation polymerization (KCTCP) with Ni2+ salts, all have one regiodefect distributed along the polymer backbones. The irregularity created by these defects can be split up into three components, i.e., the nature of the defect, the position of the defect, and the additional inhomogeneity created by mixing polymers with the defect at different positions. In this research, the influence of these three parameters on the chiral expression of poly(3-alkylthiophene)s (P3ATs) is investigated separately for the first time. A series of chiral P3ATs with one tail-to-tail (TT) or head-to-head (HH) defect in different positions is synthesized by means of the Pd(RuPhos) protocol, and their chiral expression and that of their mixtures are studied via UV–vis and circular dichroism (CD) spectroscopy. For the polymers with an HH defect, it is found that the position at the very beginning of the polymer chain is the most optimal to obtain the largest chiral expression, and the obtained signal is even the highest ever reported for PTs in chloroform and MeOH solutions. When a TT defect is incorporated into the polymer, the chiral expression is much weaker, and the most optimal position of the defect is a little shifted toward the middle of the chain compared to their HH analogues. For the mixtures of the polymers with an HH defect, a weighted average of the signals of its constituents is obtained, but for the mixtures of the polymers with a TT defect different results are obtained. When 25% of each polymer is mixed, no chiral response is obtained, and when more of the polymers with the defect more toward the chain ends are incorporated, a chiral response higher than that of any of the component polymers is recorded. This shows that the chiral expression is not only influenced by the nature or the position of a defect, but also by the mixing of polymers with a defect in different positions.

Magnetization reversal and emergent magnetic monopole-like state in square artificial spin ice vertex with defects

We have investigated the micro-magnetic behavior as well as magnetization reversal of dipolar coupled magnetic nanoislands with strong shape anisotropy arranged in a square artificial spin ice geometry. Our 0 K-temperature simulation results show that metastable two-in two-out state is stabilized at remanence of regular configurations. A complex interplay of defects and dipolar interaction leads to a predictable three-in one-out or three-out one-in higher energy state. Switching of the magnetic states is defined by the reduction of the no. of high-energy head-to-head or tail-to tail magnetic state.

Conductive tail-to-tail domain walls in epitaxial BiFeO3 films

The complex conductive behavior of ferroelectric domain walls is attracting more and more attention for their potential application as an independent nanoelectronic component. For the (001) epitaxial BiFeO3 films, we find that the domain wall conductivity varies among 71° domain walls, with tail-to-tail (T-T) domain walls more conductive than head-to-head (H-H) and head-to-tail (H-T) ones. Furthermore, it is observed that most of the conductive areas are composed of two parallel lines around the T-T domain walls. These experimental results can be well simulated by our theoretical model based on the polarization configuration and a tunneling mechanism. Our work will help to understand the mechanism of domain wall conductance in ferroelectric materials and further promote the usage of domain walls in advanced nano-devices.

Interactions of charged domain walls and oxygen vacancies in BaTiO3: a first-principles study

Ferroelectric domain walls have been promised for some potential applications due to their unique properties. In particular, the electrical conductivity of charged domain walls (DWs) allows a new dimension to ferroelectric functionalities. In this work, we construct two representative types of charged DWs, i.e. head-to-head (HH) wall and tail-to-tail (TT) wall, and employ the first-principles method to study the electronic structure of these charged walls in BaTiO3 and the interactions between them and oxygen vacancies. It is revealed that the HH walls show the n-type conductivity, but the TT walls show the p-type conductivity. While embedded oxygen vacancies attract the TT wall and repel the HH wall, the interaction between the walls and oxygen vacancies depends on the vacancy occupation. This interaction enhances the conductivity of HH walls and reduces the conductivity of TT walls, and in particular a TT wall in binding with oxygen vacancies will drive the transition of p-type wall conductivity into n-type wall conductivity. The interaction of these walls with oxygen vacancies is discussed using the electrostatic model. This work represents a comprehensive understanding of electrical transport of charged DWs in ferroelectrics and possible roadmaps for manipulation.

Cationic polymerization of isoprene using CF3COOD/TiCl4 initiating system: A new view on the polymerization mechanism

Cationic polymerization of isoprene with CF3COOD/TiCl4 initiating system has been studied under different experimental conditions. It was shown that trans-1,4 unit with different types of enchainment (regular head-to-tail and inverse head-to-head and tail-to tail) is a dominant structural unit of unsaturation part of polymer chain. The structure of head and end groups was established and mechanism of their formation was proposed. It was also demonstrated that initiation by deuterium ion occurs only at the very beginning of the polymerization followed by chain transfer to double bond of polymer with elimination of proton, which then initiates the growth of new chain. The synthesized polyisoprene is characterized by reduced unsaturation that is consistent with occurring of two side reactions: chain transfer to polymer and “polymerization” of olefinic double bonds of macromolecule.

Predicting the Binding Mode of 2-Hydroxypropyl-β-cyclodextrin to Cholesterol by Means of the MD Simulation and the 3D-RISM-KH Theory.

It has been found that a cyclodextrin derivative, 2-hydroxypropyl-β-cyclodextrin (HPβCD), has reasonable therapeutic effect on Niemann-Pick disease type C, which is caused by abnormal accumulation of unesterified cholesterol and glycolipids in the lysosomes and shortage of esterified cholesterol in other cellular compartments. We study the binding affinity and mode of HPβCD with cholesterol to elucidate the possible mechanism of HPβCD for removing cholesterol from the lysosomes. The dominant binding mode of HPβCD with cholesterol is found based on the molecular dynamics simulation and a statistical mechanics theory of liquids, or the three-dimensional reference interaction site model theory with Kovalenko-Hirata closure relation. We examine the two types of complexes between HPβCD and cholesterol, namely, one-to-one (1:1) and two-to-one (2:1). It is predicted that the 1:1 complex makes two or three types of stable binding mode in solution, in which the βCD ring tends to be located at the edge of the steroid skeleton. For the 2:1 complex, there are four different types of the complex conceivable, depending on the orientation between the two HPβCDs: head-to-head (HH), head-to-tail (HT), tail-to-head (TH), and tail-to-tail (TT). The HT and HH cyclodextrin dimers show higher affinity to cholesterol compared to the other dimers and to all the binding modes of 1:1 complexes. The physical reason why the HT and HH dimers have higher affinity compared to the other complexes is discussed based on the consistency with the 1:1 complex. On the one hand, in case of the HT and HH dimers, the position of each CD in the dimer along the cholesterol chain comes right on or close to one of the positions where a single CD makes a stable complex. On the other hand, one of the CD molecules is located on unstable region along the cholesterol chain, for the case of TH and TT dimers.

α,β-Unsubstitutedmeso-positioning thienyl BODIPY: a promising electron deficient building block for the development of near infrared (NIR) p-type donor–acceptor (D–A) conjugated polymers

Development of new ultra low bandgap (Eoptg < 1 eV) π-conjugated D–A polymers consisting of α,β-unsubstitutedmeso-positioning thienyl BODIPY.

Inversion Boundaries and Phonon Scattering in Ga:ZnO Thermoelectric Compounds.

We investigated the high-temperature thermoelectric properties of Ga:ZnO bulk compounds, synthesized using a simple and scalable solid-state process. The effects of a low gallium content (x ≤ 0.04 in Zn1-xGaxO1+x/2) on the structural features and electrical/thermal properties are reviewed. Transmission electron microscopy analyses showed that 2D, nonperiodic defects had formed from a doping content as low as x = 0.01 Ga. The structural description of these nanoscale interfaces is, for the first time, carefully investigated in such low-Ga-content samples by HAADF-STEM analyses combined with structural modeling. It was found that the formation of head-to-head inversion twin (h-IT) boundaries and tail-to tail inversion boundaries (t-IB) in the bulk compounds is responsible for strong phonon scattering, while maintaining relatively good electrical conductivity and thereby enhancing the thermoelectric properties. The absolute value of the Seebeck coefficient decreases abruptly from 475 μV/K for x = 0 down to 60 μV/K for x = 0.005 at 350 K. At the same time, the electrical resistivity drops from 1 ohm cm for x = 0 to 1.7 × 10-3 ohm cm for x = 0.005. For higher Ga additions (x > 0.01), the increase in electrical resistivity is likely linked to the formation of interface defects at a larger extent in the wurtzite structure. The thermal conductivity also drops sharply with the increase in the Ga content from ∼33 W/m K for x = 0 to ∼8 for x = 0.04 at 350 K. This study is progress toward the synthesis of other thermoelectric materials where nanoscale interfaces in bulk compounds provide tremendous opportunities for further enhancing both the phonon scattering and the overall figure of merit.

Influence of 90° charged domain walls on the electrocaloric effect in PbTiO3 ferroelectric thin films

The electrocaloric (EC) effect in PbTiO3 ferroelectric thin films (FETFs) with an array of partially compensated head-to-head (HH) and tail-to-tail (TT) 90° charged domain walls (CDWs) has been studied by using a phase field method. The calculation results indicate that the magnitude of the adiabatic temperature change ΔT increases with the diminution of the charge density (ρ*), in which ρ* is provided by charged defects or band bending. In particular, a negative EC effect caused by the direction difference between the applied electric field and the dipole is found near the HH and TT domain walls when ρ* > 2.0. The EC strength |ΔT|/|ΔE| is 0.020 K cm kV−1 with the positive ΔT = 2.03 K at the external dimensionless electric field Eb*=0.08 (ΔE = 104 kV cm−1). These results indicate that the CDWs can provide an efficient way to adjust the EC effect of FETFs for refrigeration applications at room temperature.

Control of the magnetic vortex chirality in Permalloy nanowires with asymmetric notches

We have investigated the motion of vortex domain walls passing across non symmetric triangular notches in single Permalloy nanowires. We have measured hysteresis cycles using the focused magneto-optical Kerr effect before and beyond the notch, which allowed to probe beyond the notch the occurrence probability of clockwise (CW) and counter-CW (CCW) walls in tail-to-tail (TT) and head-to-head (HH) configurations. We present experimental evidence of chirality flipping provided by the vortex–notch interaction. With a low exit angle, the probability of chirality flipping increases and here with the lowest angle of 15°, the probability of propagation of the energetically favored domain wall configuration (CCW for TT or CW for HH walls) is ≈75%. Micromagnetic simulations reveal details of the chirality reversal dynamics.

Exploring the transcription activator-like effectors scaffold versatility to expand the toolbox of designer nucleases.

BackgroundThe past decade has seen the emergence of several molecular tools that render possible modification of cellular functions through accurate and easy addition, removal, or exchange of genomic DNA sequences. Among these technologies, transcription activator-like effectors (TALE) has turned out to be one of the most versatile and incredibly robust platform for generating targeted molecular tools as demonstrated by fusion to various domains such as transcription activator, repressor and nucleases.ResultsIn this study, we generated a novel nuclease architecture based on the transcription activator-like effector scaffold. In contrast to the existing Tail to Tail (TtT) and head to Head (HtH) nuclease architectures based on the symmetrical association of two TALE DNA binding domains fused to the C-terminal (TtT) or N-terminal (HtH) end of FokI, this novel architecture consists of the asymmetrical association of two different engineered TALE DNA binding domains fused to the N- and C-terminal ends of FokI (TALE::FokI and FokI::TALE scaffolds respectively). The characterization of this novel Tail to Head (TtH) architecture in yeast enabled us to demonstrate its nuclease activity and define its optimal target configuration. We further showed that this architecture was able to promote substantial level of targeted mutagenesis at three endogenous loci present in two different mammalian cell lines.ConclusionOur results demonstrated that this novel functional TtH architecture which requires binding to only one DNA strand of a given endogenous locus has the potential to extend the targeting possibility of FokI-based TALE nucleases.

Poly(3-alkylthiophene) with tuneable regioregularity: synthesis and self-assembling properties

This work reports a synthetic strategy to generate poly(3-alkylthiophene)s (P3ATs) with joint-simultaneous control of the molar mass and the regioregularity. A series of chiral P3ATs with different regioregularities is synthesized using a Pd(RuPhos)-catalyzed chain-growth polymerisation. All polymers have molar masses and polydispersities (PDI) that lie within a narrow region. Furthermore, it is shown that the Pd-catalyst forms all kinds of couplings [head-to-tail (HT), tail-to-tail (TT) and head-to-head (HH)] to a similar extent, which allows insertion of predictable amounts of regio-irregularities into the polymer chain. This enables a thorough study of the influence of the regioregularity on the properties of P3AT, which was performed using UV-vis and circular dichroïsm (CD) spectroscopy, differential scanning calorimetry (DSC) and atomic force microscopy (AFM) measurements. Unexpectedly, it is found that under “kinetic” conditions the highest crystallinity, π-stacking, supramolecular organisation and chiral expression are not obtained for fully regioregular P3AT with 100% HT couplings, but that a small amount of regio-irregularity increases these properties and the chiral expression. Under “thermodynamic” conditions (after annealing, very slow solvent evaporation or very slow cooling from the melt), this effect is less pronounced or not found. This behaviour can be explained by a higher degree of motional freedom within the non-perfect polymer chains due to the increased steric repulsion from the HH-couplings, which leads to a more easy stacking under “kinetic” conditions.